N1-Acetylspermidine hydrochloride, an acetyl derivative of spermidine, serves as a substrate for polyamine oxidase and selectively elevates its levels in human colorectal adenocarcinomas.

3-Methylhistidine belongs to the class of organic compounds known as histidine and derivatives. Histidine and derivatives are compounds containing cysteine or a derivative thereof resulting from reaction of cysteine at the amino group or the carboxy group or from the replacement of any hydrogen of glycine by a heteroatom.

(Ethoxymethyl)benzene is a human endogenous metabolite.